rinsche



April 28, 1931. RINSCHE; 1,802,927

CALCULATING: MACHINE Filed Dec. 3, 1923 '7 Sheets-Sheet 1 ,-I TTORNE Y April 28, 1931. F. c. RINSCHE CALCULATING MACHINE Filed Dec.

7 Sheets-Sheet 2 I INVENTOR April 28, 1931. F. c. RINSCHE 1,802,927

I CALCULATING MACHINE Filed Dec. 5, 1923 '7 Sheets-Sheet 5 1X V/i/VTOR April 28, 1931- F. c. RINSCHE CALCULATING MACHINE Filed Dec. 3, 1923 7 Sheets-Sheet 4 A 7701mm April 28, 1 F. c. RINSCHE CALCULATING MACHINE Filed Dec. 5, 1923 '7 Sheets-Sheet 5 1&02327 April 23, 1931- F. c. RINSCHE CALCULATING MACHINE 5 1923 '7 Sheets-Sheet 6 Filed Dec.

lVl iE/VTOR April 28, 1931.

F. C. RINSCHE Filed Dec. 3, 1923 Q w: A

'7 Sheets-Sheet 7 IN VENTOA I), f Q M4, M, 1% 214% Patented Apr. 28, 1931 UNITED STATES PATENT oFFic FRANK C. RINSCHE, OF DET'RGIT, MICHIGAN, ASSIG'NOR *I'O IBURRQUGHS ADDING MA- CHINE COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN CALCULATING; rmonrnn Application filed December 3, 1923. Serial No. 678,140.

This invention relates to calculating machines, and more particularly to the type adapted expeditiously to perform calculaa I a o u n I 5 tions involving multiplication. and division,

as well as perform the simpler computations of addition and subtraction:

Ob ects of my invention, among others, are

to equip calculating machines with an im-,

control mechanisms for differentially pro-- polling the actuators for the accumulator; to provide improved detent mechanism for restraining actuation of the driving arms for the accumulator actuating devices of lower denominations, when the same are not to be controlled during dividing and multiplying operations by the amount determining con" trol means of the multiplying and dividing attachment set' to represent the divisor of a division problem or the multiplicand of a multiplication problem; to provide improved means for conditioning the machine for multiplication or division; and equip the machine with a counter actuated through novel means to display the quotient, when the machine is used to perform division, or the multiplicand when the machine is used to perform multiplication.

With the above and incidental objects in view, the invention consists in certain novel features of construction and combination of parts, the essential elements whereof are recited in the appended claims and the preferred form of embodiment of which is de scribed in detail hereinafter and illustrated in full in the accompanying drawings which form part of this specification.

Of said drawings, Fig. lis a perspective view of a. machine embodying my invention,

the machine being shown set for multiplication, with the auxiliary control carriage in its second or tens columnar position and with the-parts shown in normal or home condition; Fig. 2 is a perspective view of the control or indexing stop unit for the first or units order represented on the auxiliary control carriage; Fig. 3 is a perspective view of one of the indexing stop units representing the tens and higher denominations; Fig. 4 is a right-hand side elevation showing the machi .e in normal condition with the casing of the calculator removed; Fig. 5 is a horizontal, section alized, plan view, as viewed from the rear, of a somewhat diagrammatic nature, showing the indexing stop units and fixed stop arms on the auxiliary control carriage and parts cooperating therewith, the section being taken substantially on the line 5-5 of Figs. 4 and 7 and with the control carriage in. its second or tens ordinal position; Fig. 6 is an enlarged sectional view on the line 66 of 9, show ing one of the counter wheels and its spring pressed turn-to-zero pawl in engagement with the turn-to-zero notch in the supporting shaft; Fig. 7 is a vertical longitudinal section through the machine taken just within the righ"-hand side frame and exposing to View the various mechanisms appropriate to the uni-ts order; 8 is a longitudinal section through the counting mechanism on the line 8--8 of Figs. i and 7 showing the normal relation of the turn-to-zero pawls on the wheels to the notches in the supporting sh aft; Fig. 9 is a similar section, through part of the counting mechanism, but is foreshortened and shows the supporting shaft shifted to its turn-to-zero position so that its notches will engage the turn to-zero pawls and restore the counting wheels to zero when the shaft is rotated; Fig. 10 is a fragmentary sectional detail showing one of the restraining latches in latching relation with its appropriate spring-pressed driving arm; Fig. 11 is a right side elevation of the multiplying and dividing attachment with some parts in section and others broken away, showing the parts in the position which they assume when the operating crank has been given one-half of its stroke during a multiplying operation with the first or units indexing stop unit in its 3 position and the auxiliary control carriage in itsfirst or units columnar position; Fig. 12 is a. skeletonized sectional view, taken just within the right hand frame plate of the multiplying attachment, and shows the positions which the parts assume when the operating crank has been given one-half of its stroke during a dividing operation, with the units indexing stop unit in'its 3 position and the auxiliary control carriage in its first or units columnar positions; Fig. 13 is a dctail side view of certain of the parts disclosed in Fig. 11, showing them in the positions which they assume when the manually operated control frame has been rocked to permit operation (if the depressible keys of the calculator and lock the operating crank against actuation, hence disabling the multiplying and dividing attachment; Fig. 1-4: is a vertical transverse sectional view, showing the counting mechanism and the auxiliary control carriage in rear elevation, the section be ing taken substantially on the line 14-14 of Fig. 4; Fig. 15 is an enlarged fragmentary rear view of the lower parts of the quotient and multiplier pawls and their carrying arm of one order and the upper end of the operating lever with its roller in disabling alignment with the quotient pawl; Fig. 16 is a detail perspective view, looking from the rear, of the, rock cradle or frame and associated pawl for disabling the multiplying and dividing attachment and permitting operation of the depressible keys, when in one position, and for enabling the attachment, when in its other position; Fig. 17 is a horizontal sectional view through the multiplying and dividing attachment, the section being taken, in slightly different planes but substantially on the line l7-17 of Figs. 11 and 14, with the manually set indicating wheels on the control carriage shown in plan elevation and the machine set for multiplication with the parts in normal condition; Fig. 18 is an unwrapped or developed view of one of the counting wheels to show the series of quotient and multiplier digits; Fig. 19 is a horizontal section on the line 19-19 of Fig. 11-, illustrating the shiftable sight slide in adding (multiplying) position to enable reading of the multiplier displayed on the counting wheels; Fig. 20 isan enlarged fragmentary sectional View taken through the accumulating section at the front end of the machine; Fig. 21 is a fragmentary front view of the left-hand portion of the control carriage, showing the manual set lever, for conditioning the machine for multiplication and division, in subtraction (division) position; Fig. 22 is a detail enlarged section taken on the line 2222 of Fig. i l, the section being taken through the control lever and associated parts; and Fig. 23 is a detail section on the line 23--23 of Fig. l, showing the connections between the operating crank and the connecting link extending to the main operating cam.

As already stated, my invention contemplates the use of the multiplying and. dividing mechanism or attachment in connection with a commercial form of calculating machine now on the market, the combination being efiected in such a manner that'the calculating machine may be used in its ordinary way, without change, and independently of the multiplying and dividing. attachment, to perform the simpler operations of addition and subtraction. While I have shown my invention applied to the well-known commercial form of Burroughs calculator, it is to be understood that it is susceptible of use with other kinds of calculators and may, if desired, be incorporated in the machine as an integral mechanism thereof. The Burroughs calculater is a key-driven machine comprising, in general, an accumulator, consisting of a plurality of denominational numeral wheels, differential actuating devices, one for each accumulator wheel, and a multiple order l ey board including banks of keys, one bank for each actuating device. This calculator, with my invention applied, may be used with accuracy, expediency and rapidity to perform operations of addition and subtraction, as is well understood in the art, and may also be used, but without the same facility or certainty, to perform computations involving multiplication and division. For the purpose of performing the more intricate computations of multiplication and division with certainty, dispatch, and but little experience or training on the part of the operator, I have equipped the calculator with an attachment comprising, in general, an ordinally shiftable auxiliary control carriage, carrying manually set control or indexing stop units; an operating crank; driving arms driven through springs by the crank for ropelling the ditferentialactuat'rng devices or the ac-.

cumulating wheels under the control of the indexing stop units which are adapted to be set by finger pieces to represent one of the factors of a multiplying or dividing problem and each of which comprises complementary arranged stepped plates; means for shifting the auxiliary control carriage from order to order relative to the accumulator actuating devices; a lever and connections on the carriage for shifting the control units'to selectively position their stepped plates into opprative or effective alignment with the driving arms so that the accumulator actuating devices are moved extents proportional to the value represented by the setting of the control units during a multiplying operation and complemental extents during a dividing operation and mechanism comp-rising counting wheels and actuating devices for displaying 'the multiplier of a multiplication problem and. the quotient of a division problem. For

the sake of convenience, this attachment will be referred to as the multiplying attachment or section, although it is understood that it is also used in performing the process of division and other computations.

Burroughs caZcuZatbr The well-known form of Burroughs calculator, to which I have applied my invention, is fully illustrated and described in the Horton Patent No. 1,326,504, with some slight modifications, as will be pointed out presentand in order to identify some of the parts shown in the present drawings more readily,

I will utilize the same reference characters as employed for similar parts in the Horton carrying mechanisms comprise cams G and sun gears P carried by the numeral wheels, intermediate internal gear wheels C on the hubs of the sun gears E, oscillating gear carriers L, whose gears N and O' mesh respectively, with the internal gears C and the sun gears E, and levers H having teeth on their upper ends in mesh with the teeth on the carriers L and held with their studs H against the cams G by springs J, all as substantially shown and described in the aforesaid Horton patent. Gear wheels E mesh with gear wheels A and the gear wheels E are provided with circular flanges E pro vided with internal teeth and engaged by spring-pressed ratchet pawls 9, pivoted on p inions 8 meshing with oscillating segments in which derive pow-er from the depressible calculator keys 27 through connections comprising stop bars E (Fig. 7) coupled to the segments, bell-crank levers B to which the rear ends of the stop bars are pivoted and key-driven levers F connected at their forward ends by links F to the stop bars E ltwvill be understood that through these driving connections and restoring springs 28, connected to the levers B, depression of key 27 causes oscillation of the segments E and that through the medium of the gear wheels E the-aforesaid ratchet and pawl connections and the planetary gearing, the numeral wheels A are advanced in a clockwise d ircction, as viewedfrom the'right-hand side of the machine, extents, proportionate to the value of the depressed keys. The corresponding rotation of Zhecams G swings the upper ends of the levers H forward and when the high. points of the cam pass the lever studs H the levers H are operated to transmit carrying impulses, as fully explained in the above-mentioned Horton patent.

As in the Horton patent, zeroizing or Glearing of the numeral wheels A is accomplished by oscillating the gear carriers L in opposition to the springs J, the intermediate gears C being locked against rotation in a clockwise direction by engagement of the upper hooked ends of arms 2 with studs 6 on gear disc C, so that the numeral wheels A will be turned to zero by the turning of the gears N, O and P. The locking levers 2 are operated to lock the gears C through the bail 5, the cross-rod 6 of which extends through slots in the lower ends of the levers. The bail is fast on a shaft S, which is oscillated by a crank handle l/V (Fig. 1) through suitable connections, not illustrated in the present drawings but fully shown and described in the aforesaid Horton patent. lhe

.downward movement of the rod 6, as caused by the pulling forward of the crank handle W, besides operating the levers 2 also serves to drive the levers H by engaging their lower projections H to supplement the action of the springs J and insure the zeroizing action of said levers H even though the springs should fail to operate.

For the purpose of preventing backward rotation of the gears E upon forward actuation of the segments E, I employ yokeshaped back-stop 'pawls 2 provided with noses Z adapted to engage the under-cut teeth of ratchet wheel Y fast 'on the same hubs with the corresponding gear wheels E the pawls being retained in engagement with the ratchet wheels through springs B". This construction is slightly different from that shown in the Horton patent, in which the corresponding pawls engage laterally projecting teeth on the gear Wheels E and with which pawls 9 on the gears 8 coact to drive the gear wheels E said. circular flanges E (Fig. 20) with the internal ratchet teeth being employed in my construction in place of the offset teeth E on the gears E of the Horton construction. A cross-shaft 10 is provided with arms 11 having projections 11 which, when the shaft is rocked during a zeroizing operation, engage projections Z on the pawls Z rocking the awls to release them from engagement wit the undercut teeth of the corresponding ratchets Y. The arms 11 also have noses 11 which, when the shaft 10 is rocked, engage the upper extensions of the driving pawls 9 (which extend toward the right beyond the'flanges E to permit this engagement), thus rocking the pawls 9 to release them from engagement with the internal ratchet teeth, the ratchet and pawl connections being disabled to avoid any interference with the reverse rotation of the gear wheels E which accompanies a backward turning of the numeral wheels during a zeroizing operation. The shaft 10 is operated through connections with the aforesaid rock shaft S, which comprise an arm 31 having a stud l2 engaging in a slot lOll in a cam plate 13, which at its upper end has one end forked to engage a stud on an arm,10 fast on the shaft 10, all as described in the Horton patent.

. Frame of multiplying attachment J-shaped side plates 32 and 33 (Figs. 4 and 7) are fastened by pairs of screws 34 to the rear ends of the opposite side frames of the calculator and these side plates have notches 35 in their lower edges which engage over a cross-rod 36 and act as supporting guides to assist in properly positioning the multiplying section on the rear end of the calculator. The upper ends of the forward vertical arms of the side plates 32 and 33 are provided with,inwardly extending ears 30 (Figs. 17 and 21) I supporting a cross-bar 37 which is formed to constitute a track for the ordinally shiftable auxiliary control carriage, to be described later, and the vertical rear arms of the plates are connected near their upper ends by means of cross-rods 38, 39 and 40, the intermediate portions of the plates being also connected together by other cross-rods and shafts, as will be pointed out later. Operating mechanism and differential driez'ng connections of the multiplyzng attach'ment Pivotally connected near the upper end of each of the bell-crank levers B is an irregularly shaped connectlng link or arm 42 (Figs. 7 and 12) having a bayonet-shaped slot 43 in its rear end throu h which. projects a flanged supporting stu 44, projectlng laterally from a spring-operated driving arm 45, it being understoodthat there is one of these links 42 and a corresponding driving arm 45 for each denomination calculator. The driving arms 45 are suitably spaced and'loosely mounted on a cross-rod 46, supported at its ends in the side plates 32 and 33. On the same shaft 46 and suitably spaced from the driving arms 45 are vertical ly extending arms 47 having rearward extensions connected to the upper ends of springs 48, the lower ends of which are connected to rearwardly and downwardly extending projections on the driving arms 45. Each of the arms 47 carries a roller 49 which rides on the periphery of an appropriate cam-shaped plate 50 and the plates 50, there being one for each arm'47, are fast to a rock shaft 51.journaled at its ends in the side plates 32 and 33.

Fast on the right-hand projecting end of the shaft 51 (Figs. 1 and 4) is a goose-neck cam plate 52 having pivoted thereto by a shoulder screw and nut-59 the rear end of a link 53 connected at its forward end to a crank arm 54 fast to the inner end of a stub shaft 55, which has keyed on its outer end an operating crank 56, held in place on the shaft by a suitable washer and nut. The'shaft 55 is rigidly connected to and,

represented in the y suitably journaled in the upper'end of the bracket 57 which is fastened to the under side of a base-plate 58 which supports the machine.

From the above description, it will be -evident that, upon each complete rotation of the crank handle 56 (in a clockwise direction, as viewed from the right side of the machine), the crank 54 and link 53 impart a reciproeating movement to the cam plate 52, acting as a crank arm, and the shaft 51 through an arc of approximately .90 degrees, first in a clockwise and then in a counterclockwise direction and that the cams 50, fast on the shaft 51, through their coaction with the rollers 49, rock the arms 47 forwardly in variable extents and then permit the springs 48 to rock the arms rearwardly to normal position. lVhen the arms 47 are rocked forwardly in this manner, the springs 48, serving as yielding connections between the arms 47 and the driving arms 45, rock the arms 45 forwardly until they are arrested in different positions determined. by the setting of the indexing stop units to be described later. As the studs 44 on the arms 45 are seated in the forward ends of the slots 43, the links 42, levers B, stop bars E and segments E are moved forwardly proper extents to actuate the accumulating wheels and add or subtract the number represented by the settings of the control units on the accumulator. The springs 48 are stronger than the restoring springs 28 connected to the levers B. Upon return rearward movement of the arms 47, their lips 60 which extend laterally from their forward edges in front of the arms 45 engage the latter and restore them "to normal position, the arms 45 being arrested in normal position by their engagement with the shaft 51.

' In orderto automatically assist the operator in operating the machine during the first half of the stroke of the crank handle 56, at which time the greatest load is on the handle and to also provide a slight resistance to the return of the crank handle 56 during the last half of its stroke, at which time the load of the operating parts has been removed from the handle and thus provide for a smooth and easy operation of the machine throughout the entire stroke of the crank handle, a crank arm 63 (Figs. 4 and 17) is fastened to the lefthand end of the shaft 51 and is provided at its outer end with a stud to which one end of a spring 65 is connected, the other end of the spring being connected to a stud on the-1 left side plate 33. The spring 65 is normally under tension, as shown in Fig.- 4, but not sufficiently to operate the machine, and during the first half of the stroke of the crank handle 56, rotation of the shaft 51 in a clockwise direction, releases'the tension of the spring 65 which has assisted the operator in actuating the parts, but during the second half of the stroke of the handle, when the shaft 51 is rocked counter-clockwise, the spring 65 is again placed under tension, thereby providing a slight resistance to the return of the handle.

For the purpose of accurately positioning the above-described operating mechanism in its normal position, there is provided a spring-operated return arm 66 (Fig. 4) supported at its lower end on a shoulder screw 67, threaded into the right-hand side plate 32.. The upper end of the arm is provided with a stud to which is connected the forward end of a spring 68 connected at its rear end to stud on the side plate 32, the spring normally acting to retain the arm 66 in the normal position shown in Fig. 4, with itsroller stud-69 thereon, seated'in the upper end of a recess 70 of the cam plates 52. When the cam 52 moves clockwise the roller 69 rides on the edge of the-cam and stretches the spring 68. As the cam returns toward its home position shown in Fig. 4., the roller 69 moves into the slot 70 which is shaped so that the'pressure of the roller under the tension of spring 68 tends to cause the cam to occupy its home position. If the cam should be moved slightly past its home position, theroller returns it. If it is stopped slightly short of its home position, the roller acting on the edge of the cam moves the latter to final position.

A pawl 71, pivoted on the bracket 57 (Figs. i and 23) cooperates with a ratchet 72, which is mounted on the shaft and fastened to the crank arm 54 by means of a rivet. The pawl 71 is connected to a spring 73 and cooperates with the ratchet to prevent return movement of the operating crank 56 in a counter-clockwise direction, once it has been moved clockwise in its normal direction of movement from its normal position. Several teeth have been omitted from the ratchet on its lower side, thereby forming a smooth surface against which the pawl 71 bears when the handle is in normal position, the object oi this smooth surface being to allow a small amount of play tot-he handle to take care 0t any slight overthrow of it due to momentum, before the pawl engages the ratchet teeth.

' Indexing stop units and indicating wheels lln general, the means for con rolling the differential extents of movement oi the spring-operated driving arms l5, and hence oi the corresponding accumulator wheels,

the forward movements of the spring-pressed driving arms 4-5 so that the corresponding accumulating wheels are advanced a number of steps directly proportional to the value of the setting of the control units, while the other plate of each unit is employed in dividing operations to arrest movement of the driving arms 45 and hence of the corresponding accumulator wheels after the same have moved extents coinpleinental to the value represented by the setting of the control units, the units being shiftable laterally to position, the multiplying or dividing plates in operative alignment with the driving arms 45, when the machine is conditioned for multiplication or division, as the case may be and as will be described later.

From what has been stated above, it is evi dent that the process of division is carried out with my machine by repeated substraction of the divisor from the dividend, set up on the accumulator, and that this subtractive operation is performed by adding the complement of the divisor to thedividend (and successive remainders thereof), 9s being automatically added during each stroke of the operating crank 56 in a dividing operation on all of theaccumulator wheels of higher denominations than that actuated under the control of the subtracting plate 82 set to represent the digit of highest denomination represented in the divisor.

The control carriage comprises a suitably grooved slideway 75, mounted to slide laterally on the rail or track 37, and a plate 76, carrying the control units and mounted on the slideway 75 to move therewith, as will be described later. ln'order to aid in supporting and guiding the plate 76 in its sliding movement, it is provided near its "upper end with brackets or plates 74.- (Figs. 7 and 8) through holes in which the guide rod 38 extends.

As best shown in Figs; 1 and 14-, the carriage plate 76 is provided with six vertical slots 77 through which extend finger-pieces 8, projectin forwardly from the upper ends f the control or indexing stop units 79, a 7

1% and 17). Each of these indexing stop .nits'comprises a slide 80, a stepped ll1linull The nuiiiber wheels 88 with their pinions 89 are loose upon studs projecting laterally from brackets 86 (Figs. 11, 14 and 17) secured to the rear side of the carriage plate 76 and between the indexing stop units by laterally projecting lugs or ears. The indicating wheels 88 are in alignment with the banks of keys 27, 'and hence with the sight openings A through which the accumulator wheels A display their numbers, and it will be evident that when the finger-pieces 7 8 are moved to position the indexing stop units to represent the value of the multiplicand 1n a multiplying operation or the divisor in a dividing operation, the indicating wheels 88 are accordingly positioned to display to the operator the multiplicand or the divisor, as the case may be and thus assist him in properly setting the indexing stop units.

Bell-crank detent pawls 91 are pivotedat I 92 on the brackets 86 and the noses on the upper ends of their vertical arms engage the pinions 89 while lugs on the forward ends of their horizontal arms are connected to one end of springs 96 connected at their opposite end to studs on the brackets 86, the s rings being of suliicient strength to cause the pawls to properly align the numeral wheels 88 and maintain the indexing stop units in their different positions of adjustment.

From what has been said, it will be understood that the auxiliary control carriage may be shifted laterally from one order to another; in a manner to be described later, to bring the indicating wheels 88 into alignment with the banks of keys 27 of the proper denomination dependent upon the number of denominations or places represented in the -multiplicand or to be represented in the quotient, but for the present it might be assumed that the carriage is in its extreme right-hand position with the unit or righthand number wheel 88 in alignment with the units bank of keys 27 of the calculator. It might also be well to state here that the carriage plate 7 6 is mounted on the slideway 7 5 and connected thereto in such a manner that it may be given a slight shifting movement relative to the slideway, while the slideway is in stationary position, for the purpose of moving the adding plates 81 into operative alignment with the spring-operated driving the respective stops arm 45, when the machine is conditioned for performing multiplication or to bring the subtracting plates 82 into such operative alignment when the machine is conditioned for performing division. Before describing the mechanism for ordinally shifting the auxiliary control carriage, or the mechanism for conditioning the machine for multiplication or division, it will'be Well to describe first the specific construction of the adding and subtracting plates 81 and 82 and the operation of the accumulator actuating devices under their control.

The adding plates 81-for all of the indexing stop units are all alike and similarly positioned on the respective slides 80. For the sake of illustration, I have applied the naughts and digits to the stops of the adding plates shown in Figs. 2 and 3, the digits of being representative of the number of ste s of movement which the spring-operated riving arms 45 are giver when arrested by the respective stops during forward oscillation of the driving arms 45 to move the actuating devices of the accumulator differentially. For example and assuming that the machine is conditioned for performing multiplication, unit is moved to its 3 position, shown in Fig. 11, in which position 3 is displayed by the corresponding units numeral wheel 88, the 3 stop is moved into the path of movement of a lug or ear 97 extending laterally from the thickened upper end of the spring pressed driving arm 45 of units denomination, assuming that the control carriage is in units or first position, so that when the arm 45 is swung forwardly, as above described,'this 3 stop is engaged by the lug 97, as shown in Fig. 11, and hence arrests the movement of the units driving arm 4-5 after the same has been swung forwardly three steps of movement. In Fig. 11 the parts are shown in the positions which they assume when the operating crank 56 has been given one-half of its stroke of operation.

As above stated, the process of division is performed by successive additions of the complement of the divisor to the dividend (and to the successive remainders thereof) set up on the accumulator. It is understood that Os to the right of the digit of lowest order in the divisor are ignored or disregarded when the divisor is set upon the auxiliary control carriage. For example, the divisor 50 (or 500) is set up 5 by ioving the units control unit to its 5 position, as many places being pointed oil or eliminated in the quotient as there are ciphers to the right of the digit of lowest order in the divisor, as will be more fully pointed out later. As division is accomplished by adding the comple ment of the divisor, an extra 1 is added under the control of the units subtraction plate 82, and therefore this subtracting plate if the units control control unit is moved to its 3 is complementally arranged relative to the companion units adding plate 81, with respect to while the subtracting 82 for the control units of higher denominations are complementally arranged with re? spect to their companion adding plates 81 with respect to 9, as will be best understood by referring to Figs. 2 and- 3, in which I have also applied digits to the stop of the subtracting plates. Assume, now, that the machine is conditioned for performing division, in which case the subtraction plates 82 are in the zones of movement or operative alignment with the lugs 97 on the arms 45, and the units position, as before, if it is not already in such position, the units driving arm 45 (assuming that the control carriage is in its units or first position) is moved forwardly seven steps to the position shown in Fig. 12, at the end of which movement it is arrested by engagement of the lug 97 with the 7'"stop on the subtracting plate, thereb Y causing the units accumulator wheel A to e advanced seven steps to add thereon 7 with respect to 10. If at the same time one of the control units of higher order is moved to. its 3 position by its linger-piece actuating segment E nine steps to add 9 on the corresponding 78, the driving arm in alignment, there with moves forwardly'six steps, to advance the corresponding accumulator wheel A a like number of steps to add thereon 6- the complement of 3 with respect to 9. If a 0 occurs in the divisor in an order higher than the lowest denomination represented by a digit, the corresponding indexing stop unit is allowed to remain in 0 osition, and upon operation of the machine the driving arm 45 and hencethe corresponding are moved forward accumulator wheel, and all of the driving arms 45 and corresponding actuating segments E of higher orders than the arm and segment of highest order actuated under control of the control stop unit set to represent the digit of highest order inthe divisor, are actuated nine steps, the actuating cams being so constructed that the driving arms 47 and hence the unrestrained spring-operated driving arms 45 are rocked nine steps of movement upon each rotation of the operating crank 56.

When the machine is conditioned for performing multiplication, the driving arms 45 of higher order than the one controlled by the control unit positioned to represent the digit of highest order in the multiplicand must be restrained from movement, and to this end the 0 stops on the control units which are allowed to remain in zero position prevent operation of the arms 45 in alignment therewith and four arms 100, (Figs. 5, 14 and 17) secured to the carriage-plate 76 and having their rear ends in the same horizontal plane plates which is the complement of 3? actuation.

Late/Ling means for driving arms 45 of lower orders When the machine is used to perform multiplication, the control carriage is shifted from order to order from right to left, depending upon the number of places or denominations represented in the multiplier, the o crating crank 56 being given a number of stro res, with the carriage in each ordinal position, dependent upon the value of the digit in the correspondingdenominationofthemultiplier. For example, if the multiplier is 32, the crank is given two rotations with the control carriage in its units or extreme right-hand position as the digit :2 appears in the units order, and then the carriage is moved one order or place towards the left and the crank is given three rotations, thedigit 3 appearing in the tens order ofthe multiplier. When the machine is used to perform a problem in division, the carriage is shifted in the reverse direction, that is from left to right and in each ordinal position the crank is given a number of rotations dependent upon the number of times the divisor is contained in the dividend or in the portion of the dividend (or. remainder) displayedby the accumulator wheels A in alignment with and to the right of the divisor displayed on the wheels 88. It will be obvious therefore, that it is necessary to prevent operation of the actuating mechanisms for the accumulator wheels A of denominations lower than the denomination represented by the ordinal position of the control carriage. For example, if the carriage is in its extreme lefthand or sixth position, the five actuating arms 45 of lower denominations are not under the control of the indexing stop units and it is then necessary to block these live arms against. To this end the following means are employed:

Five latches 101 (Figs-5, 7, 1.0 and 17) are loosely mounted and suitably spaced by spacing collars on a cross-rod 102 supported at its ends by the side plates 32 and 33. Thereare only five of these latches and they'are in operative alignment with the five righthand spring-operated driving arms 45, because in the particular machine disclosed in the drawings, the carriage has only a range tion takes place. on the sixth accumulator wheel aligned with the digit in the units order ot the multiplicand or divisor and represented by the position of the units indexing stop unit, so that the driving arm 45 for that particular order must be capable of movement to etlect registration, while in the five lower ordersto the right, the driving arms l5 must be capable of being locked against movement. lhe forward ends of the latches lOl are provided with noses 103 adapted to engage and ride on the upper edge of a ill-shaped hail 104: whose side arms are riveted or otherwise fastened to the rear side of the carriage plate 76. "When the carriage is in its extreme right-hand position, which is its units or first position, shown in Fi s. 14 and 17, hooks or noses 105 (Fig. 7) projecting downwardly from the forward end of the latches are,in elevated position out of engagement with laterally projecting lugs 106 on the live arms of lower denominations the lug 106 being parallel. to and to the rear of the above-mentioned lugs 97 the latches being retained in this position by the engagement their noses 103 with the top edge of the bridge of the bail 104; so that actuation of these arms 45 is permitted under the con rol of the indexing stop units. When 30 the carriage is moved one step toward the left, (as viewed from. the front) to its tens second position as shown in Fig. 5, the

bridge of the bail 10% moves beyond the zone of the units or right-hand latch 101, thus per t n;- mitting it.) spring 15)? to rock it countercloclo Wise to move its nose 1.05 in front of the lug on t units arm. 4-5, thus blocking that arm ag; 3 operation. As the carriage is stepped Jlfil toward the left, the same proe, Cedure otloclnng the driving arms 4:5 takes place in the successive orders. until when the carriage econ moved to its last or sixth position, live latches lOl are all released and locl heir IQSP-Qfiillrd driving arms against to *ard actuation In a dividing oporation, this condition is reversed as the car riageunoves from the leit to the right. With the carria in its sixth position, the five driving s 255 01 lower denominations are blocked st oper rllliill, as it is intend ild take place in these carriage is moved to its filth position 1 as viewed rowed 14) of the bail 10 ieoaeav spective driving arms 45, as the bail is brought within the zones of the latches The latches 101 have upwardly and forwardly curved tails Whose forward ends engage a cross-rod l09when the latches are in etlective latching positions, the rod serving to limit the movement of the latches to latching' position,

Zlfecms for" ordinally shifting i'hewovetrol car/wage The lower edge of the grooved slideway is formed to provide a rack 110 (Fig. 14), extending about two-thirds of its length and of sufiicient length to permit shifting of the control carriage from one extreme position to the other In mesh with this rack 11.0 at the left-hand side of the machine as viewed from the front is a gear 111 last on a shaft 112 extending longitudinally of the machine adjacent the left side thereof and at right angles to the slideway 75, the shalt-being supported near its rear end in a bracket 113, fastened to the left-hand. frame 33 in any suitable manner) and supported near its forward end in a bracket 114t- (Figs, 1 and 'l') secured to the base 58. Secured to the forward end of the shaft 112 is a hand wheel 115- otating the shaft pinion llil and as meshes with the rack 11% the contr o is shifted toward the lert or the right. case may be, on the track or rail 37;

l! on the shaft 1.12 near its rear e host shown in 14 l! and is wheel 116 with which coasts a roller s i Z projecting from an arm 118 pivoted by stud A. strong soring 119 to the tract: or rail. 3? L is connected its 11; p

on the arm 118 and at its low in the bracket l3 and stud 117 in engagement we 116 to accurately align the carriage in lccted colun'inar position 1d accidental displacement from such.

Home for somlze'on'ing machine Zion (mmi'zpmcation) 02 motmotio; s lon) n; o vice v s: "W re till riage plate 76', is secured at its rear end to the upper end of a lever 128 which carries a stud 141 projecting through a vertical slot 142m the carriage plate 76, and the lever is pivoted on a headed stud 124, threaded into the slideway 75. The slot 142 is of. the same width as the diameter of the roller stud 1411 I but slightly greater in its vertical dimension, thereby allowing a slight vertical-movement of the stud 141 in the slot 142 without binding when the levers 123 and 128 are shifted by the finger-piece 126 from their adding position (shown in Fig. 1) to their subtracting position (showii in Fig. 21) or vice versa, the angular movement of the lever 128 being such as to cause this slight vertical movement of the stud 141 in the slot 142. N ow, as the spring-pressed roller 117 exerts suliicient pressure on the star wheel 116 to prevent turning of the gear 111, in mesh with the rackllO on the slideway 75, unless the operating wheel 115 is. rotated,-and, as the stud 124 is fast in the slideway 75, this stud becomes the fulcrum about which the lever 128 turns when moved from one position to another and the stud 141 acts on one side or the other of the slot 142 and shifts the carriage plate 7 6 relative to the slideway 75, the plate being shifted toward the right, as viewed in Fi 1 1, when the lever is moved from the adding position, shown in Fi e. 1 and 1 1, to the subtracting position shown in Fig. 21, there by shifting the subtracting plates 82 into operative alignment with the spring-operated'driving arms as shown in Fig. 5. Conversely when the lever 128 is moved by the finger piece 126 from its subtracting position to its adding position, the carriage plate 7 6 with its associated parts will be shifted to the right (as viewed in Fig. 1) thereby moving the adding plate 81 and the stop arms 109 into operative alignment with the driving arms 45 as shown in Fi s. 141 and 17. The stud 124 projects through a horizontal slot 144 formed in the plate 76 to accommodate the movement of the plate. 1 4

For the purpose of retaining the carriage plate 7 6 in its, adding or subtracting position on the slideway 7 5, the lower end of the lever 128 is provided with a plate 132 (Figs. 14-,

I 21 and 22) slidably mounted for vertical movement thereon hymeans of studs 135 on the lever 123- projecting through vertical slots 136 formed in the plate. The stud 124 also projects through a central vertical slot 137 in said plate. The plate 132 carries at its lower enda roller stud 130, extending into a positioning slot 131 in the slideway 75, a larger slot 133 being formed in the carriage plate 7 6 to permit free movement of the roller stud therein and co-action of the stud in the slot 131. Both ends of the slot 131' form dwells with a rise on the upper edge pf the slot between them, the ends of the-slot being nearer the pivot pin 124 than istherise. A; spring 139, connected at its upper end to a stud on the lever 128 and at its lower end to a stud on the slide plate 132, forms a yielding connection between the lever and the slide plate so that when the lever 128 is moved from subtracting to adding position, or vice versa, the roller stud 130 on the lower end of the slide plate 132 passes over the rise between the two ends of the slot 131 and as the roller moves into one end of the slot, the spring 139 draws theslide plate upwardly and firmly seats the roller stud 130 into such end of the slot 131 and retains the same therein thereby firmly holding the carriage plate 76 in its set position on the slideway. The extent of movement of the carriage plate 760n the slideway 7 5 in either direction is limited by the engagement of the shouldered supporting studs 121 with the extremities of the slots 122, through which the studs project.

Numeral wheels of counter mechanism and sag/at slide the control carriage, these wheels being loose ly mounted on a shaft 14-8, supported in suitable hearings in the side plates 32 and 33, as loest shown in Figs. 8 and 9. The wheels are suitably spaced from each other by spacing collars between their hubs. As best seen in Figs. 14 and 18, the peripheries of the counting wheels have two sets of series of digits reading in opposite directions, with their 0 s digits being used to indicate the quotient in a dividing operation and the unshaded numloers being used to indicate the multiplier in a multiplying operation.

The numerals on the readin counting wheels, are displayed t rough sight openings 142 (Figs. 1 and 19) in a curved cover plate 150, positioned over the counting wheels and mounted by ears on the cross rods 38 and 40. The openings 149 are substantially the same width as the numeral wheels, but

line of the in order that only the quotientdigits or the in. alignment, the left-hand shaded wheels, so that only one set of numerals are visible at a time through the half-closed si ht openings 149. The. slide plate is slidalwly mounted at one end on a shouldered stud 153, fast to the cover plate 150 and projecting through a slot in the plate 151, and at its opposite end by a shouldered finger-piece 154, the rear stud on the finger-piece projecting into a slot in the cover plate. The finger-piece is employed to shift the slide plate 151 to adding or subtracting position, represented by the letters A'and respectively, in Fig. 1, so that when the slide plate is moved to the right, as shown in Fig. 1, only the digits representing the multiplier will be visible to the operator, while when the slide is shifted to the left to subtracting position, only the figures representing the quotient will be visible. It is understood that when the machine is conditioned for addition or subtractioh by. shifting of the finger piece 126, the slide plate 151 should be similarly shifted.

Ummter wheel actuating mechanism Fastened on one end of the hub of each of the numeral wheels is a ratchet wheel 157 (Figs. 7, 8, 11 and 12) and on .the enlarged portion of each hub is loosely mounted a pawl carryin plate 158 having pivoted at its lower on viewed from the front of the machine, an operating pawl 160 called the quotient pawl herein, spaced from the pawl-carrying plate by a suitable spacing collar. On the opposite side of the lever or arm 158 is pivoted at 165 on o crating pawl 159, designated herein as the multiplier pawl. Springs 161, connected at their forward ends to studs on their respective pawl-carrying arms 158-and at their rear ends to the cross-rod 40, serve to normally retain the pawl-carrying arms in normal position, in which position, as shown in Fig. 7, they contact with the forward edge of a cross-plate 162 secured at its ends to the side plates 32 and 33.) Springs 163, connecting forward extensions of the companion pawls 159 and 160, tend to rock the upper ends of the respective pawls into engagement with the ratchet wheels 157, but while the arms 156 are in normal engagement with the forward edge of the cross-plate 162, the

rear edges of the quotient pawls 160 likewise engage this edge, while the rear sides of downwardl extending arms 164 on the multiplierpaw s also engage this edge and hence the pawls are held out of engagement with theratchet wheels against the influence of p the springs-163.

Inorder to accurately align the numeral wheels: 147 in their set positions and prevent overthrow of the same, when actuated by the pawls 159. and- 160, as will be described presently, there are provided six bell-crank levers 166, one for each ratchet wheel 157 and mounted on the cross-rod39. The forward and to the right thereof, as

ends to the cross-rod 40, act firmly to retain the roller studs 169' in contact with the ratchet wheels 157.

Upon each stroke of the operating crank.

56, the pawl-carrying arm 158 appropriate the counter wheel 147 corresponding to the ordinal position of the control carriage is oscillated, and either the pawl 159 or 160, de-

pendent upon whether the machine is cond1- tioned for multiplication or division by the finger piece 126, coacts with the corresponding ratchet wheel 157 (while the other pawl is disabled) to advance the counter wheel one step, that is to say, one step in a clockwise direction if the machine is conditioned for subtraction (division), or one step in the opposite direction if the machine is conditioned for addition (multiplication). This means for rocking the particular arm 158, corresponding to the ordinal position of the carria-ge, and rendering the multiplier or quotient pawl thereon ineffective, dependent upon whether the machine is conditioned for multiplication or division, will now be described.

A bell-crank lever 170 (Figs. 11', 12 and 14) is pivoted at 171 to an extension of the units number wheel supporting bracket 86 and carried at the upper end of the bell cranklever is a stud 167, which, when the machine is conditioned for multiplication, is positioned (as shown in Fig. 14) behind the quotient pawl 160 of the denomination corresponding to the ordinal position of the control carriage, and at the same time the stud and lever are to be left (as viewed from the rear) of the tail 164 of the companion corresponding toIthe columnar position of the control carriage, the roller being moved into alignment with the successive cams as the control carriage is shifted to the successive ordinal positions. A spring 173 connected at its rear end to a stud on the lever 17 O and at its forward end to a stud on the bracket 86 for the units order, normally retains the operating lever 17 0 in the position columnar shown in Fig. 7 with the forward end of a forwardly extending projection 174 on the dent, that, upon each operation of the operating crank 56, a projection 17 5 of. the particular cam plate 50 in alignment. with the roller 172 on the lever 170 counts with the roller, thereby rocking the lever 170 counterclockwise an invariable extent, to the position shown in Figs. 11 and 12, the lever being restored to its normal position by its spring 173 during the last half stroke of the operating crank. During the forward movement of the upper end of the lever 170, when the machine is conditioned for multiplication, its roller stud 167 contacts with the rear edge of the pawl supporting arm 158 of the denomination corresponding to the position of the carriage and rocks the arm and the pa-wls 159 and 160 to the position shown in Fig. 11. As the stud 167 is out of alignment with the tail 164 of the pawl .159, the sprin about its pivot as t is tail 164 moves out of engagement with the forward edge of the cross-plate 162, the; pawl then riding freely over the teeth of the ratchet wheel 157. During this forward movement, the companion quotient pawl 160 is held out of engagement with the ratchet wheel and into engagement with a limiting pin 180 on the arm 158 by which also serves to hold this the stud 167 v pawl in its disabledposition during the return movement of the arm 158 by its spring 161, It will lie-evident that during this return movement, the multiplier pawl 159, being in engagementwith one of the teeth of wheel and hence the-number wheel, one step in a counterclockwise direction to add 1 on the counter wheel whose multiplier digits, brought to the reading line, are then viewed through the sight opening in the slide 151. With the machine conditioned for subtraction, the stud 167 when moved forwardly as before, engages the tail 164 of the multiplier pawl 159, but clears the rear edge of the quotient pawl 160, so that the quotient pawl, when the arm 158 is rocked forwardlyby the stud 137, rotates the correspondingratchet 1 57 and the number wheel 147 in a clockwise direction to add 1 thereon, and upon return movement of the arm 158 the quotient pawl rides freely over the teeth of the ratchet while the multi lier pawl 159 is held out of engagement wit the ratchet teeth by the en- 'agement of its tail 164 with the stud 167.

uring dividing operations the quotient digits on the number wheels are viewed through the sight openings in the slide 151 which has been moved to its subtracting (dividing) position.

ing a nose 163 rocks the pawl 159 Zeroz'ez'ng 0f the counter wheels 14? At the end of each multiplying or dividing calculation, or before the machine is used to perform a new problem, the counter wheels 147 are turned to zero. For this purpose each of the counting wheels 147 has pivoted-on its inner side a pawl 178 (Figs. 6, 8 and 9) hav- 179 projecting through a cutaway portion in the hub of the wheel, a spring 180, fastened at one end to the pawl and encircling the hub of the wheel at its other end, serving to retain the nose 179 in such cut- .away portion. Normally, the nose 179 of the pawl rides freely on the periphery of the supporting shaft'148, when the wheels are rotated by the actuating pawl 159 or 160 during an operation ofthe machine. The

supporting shaft 148 is suitably supported for sliding movement in bearings in the side Dlates 32 and 33, and has-enounted on its left-hand end (as viewed in Fig. 8) a collar,

181, which prevents displacement of the shaft toward the right, and has mounted on its opposite end an operating handle 182, the innor-lend of the hup 184 of which is cored out to house a coiled spring 183 which is compressed between the side plate 32 and the end of the cored-out portionto normally retain the shaft 148 inthe position shown in Fig. 8, in which position a notch 185 (Figs. 8 and 14) formed in aflange 186 on the inner end of the hub 184 engages the lower offset end of a stationary latch 187, fast on the plate 32, to prevent rotation of the crank 182'and hence of the shaft 148 when in normal position. When the counting wheels are to be turned to zero, the shaft 148 is slid toward the left by the handle 182 and against the tension of its spring 183, moving the notch 185 out of engagement with the latch 187, as shown in Fig. 9, and bringing shouldered recesses 188 in the shaft into the path of the noses 179 of the pawls 178, so-that when the shaft is rocked counter-clockwise, as viewed in Fig. 6, by the handle 182, the shoulders of the recesses pick up the pawls 178 and restore the numeral wheelsfto zero. During this rotation of the handle 182 and shaft 148, the flange 186 is positioned between the plate 32 and the lower offset end of the latch 1 87 and thus the latch prevents the shaft and handle from being slid toward the right to normal position until at the end of a com pleterotation of the handle, at which time thev notch 185 is in alignment with the latch 187 and the numeral wheelshave arrived at 0 positions.

Disabling multiplying attachment tachment, by locking the operating crank 56 the outer end of the shaft 196 is a hand lever.

or crank 197. The lower tie-bar 194 extends under the rear ends of all of the connecting arms or links 42, as best illustrated in. Figs,

7 and 11,'in which figures the rock frame 191 18 shown in such position that the upper ends of the forward vertical portions of the bayonet slots 43 in the links 42 rest on "thestuds 44 on the operating arms 45, so that when the latter are operated the links and differential mechanisms are reciprocated, as above described. When the rock frame 191 is rocked forwardly by its handle 197, to the position shown in l ig. 13, to disable the multiplying attachment it will be seen that the lower tiebar 194 engages and raises the rear ends'of the links 42 to move the vertical portions of the bayonet slots 43 out of engagement with the studs 44 and that in this condition,

the links 42 may be moved forwardly with the bell-crank levers B without disturbing the driving arms 45, when the keys-27 of the calculator are operated to operate'the calculator in the usual way, the shouldered studs 44 then being clear of the forward. vertical portions of the bayonet slots so that whenthe links are reciprocated their rear endsare supported by the studs 44 as the upper edges of the horizontal portions of the slots then ride on the studs 44. hen the frame 191 is rocked from its position shown in Fig. 13 to the position shown in Figs. 7 and 11, the intermediate cross rod 194 engages the upper "edges of the links 42 and forces them downward to engage the forward vertical I portions of their slots 43 with the studs 44, if

the links do not fall to such position by'grav.- ity. The rollers 49 on the driving arms 47 (Fig. 7) are normally behind. the projections 175 on the cam plates 50 so that with the multiplying attachment enabled. when the frame is in the position shown. in Fig. 7, the keys 27 cannot be depressed because the links'42are locked to the arms 45 and the arms 45' and 47 are lecked against forward movement by the projections 175.

In order to lock the crank handle 56 and associated parts against operation, when the machine is to be operated under the control of the keys 27, the hub of the goose-neck cam plate 52 is provided, as best shown in Figs. 1 and 13, witha flanged collar 204, the flange of which is notched at 205 so that when the frame 191 is rocked forwardly to disabling position, the nose of a pawl 206 fast on-the shaft 196 engages the shoulder of the notch and hence blocks movement of cam plate and prevents operation of the operating crank 56.

The rock frame 191 is yieldingly retained in one or the other of its two positions of adjustment by a roller stud 198 mounted on the rear end of an arm 199 pivoted to the side frame 32, a spring 200 connected to the arm 199 serving to yieldingly retain the roller 198 in engagement with the upper edge of the side plate 192 of the frame. When the frame is in its rear position, in which position, as shown in Fig. 7 it permits the studs 44 to engage in the vertical portions of the slots roller 198 engages a curved depression or notch 201 on the plate 192 and when the frame is in its disabling position, shown in Fig. 13, the roller 198 is seated in a similar depression 202 to the rear of the depression 201, the frame being thus held in its position of adjustmen against accidental displacement. I

Means for locking machine against operation during zeroizing of counter To prevent operation of the machine when the counter wheels 147 are being turned to zero, as above described, there is pivotedto the side plate 32' by screw stud 208 (Figs. 4 and 11) a bell-crank lever 209 whose upper 43, the

end is bent in the direction of the side plate 32 to form a lug 210 (Figs. 4 and 14). The lower end of the lever 209 is provided with a slot 211 into which projects a pin 212, projecting inwardly'from the downwardly extending end 217 of a goose-neck arm 213 fast to the right-hand end of a cross-shaft 214 journaled in brackets 215 which are secured to and extend forwardly from the side plates 32 and 33. A spring 216 connected at its opposite ends to the arm 213 and a stud on the calculator frame, acts to normally retain the end 217 of the arm 213 in engagement with the rear side of the roller stud 69 on the arm 66. When the arm 66 is rocked forwardly, during operation of the machine, by the operating cam plate 52, as above described, the

spring 216 is permitted to rock the arm 213 forwardly, the end 217 following up the roller stud 69, and at the same time the pin 212 moves down in the slot 211 in the lever 209,

as illustrated in Fig. 11, thus rocking the latter clockwise, as viewed from Figs. 4 and 11, to move its upper end with its lug 210 between the inner side of the flange 186 on the hub 184 of the lzeroizin'g handle 182 and the side plate 32, the lug 210 being of sufiicient width to block movement of the handle and shaft 148 toward the left, when between the hub flange and the late. When the arm 66 is rocked rearwardly to normal sition, shown in Fig. 4, the roller stud 69 ing in engagement with the end 217 of the arm 213, moves the latter rearwardly and as its pin crank 56 and to 212 moves upwardly in the slot 211 the lever Uarrt'age locking mechanism It is important that the shifting control carriage, comprising the slideway 75 and plate 7 6, be locked in any one of its columnar positions during operation of the operating also lock the operating crank 56 against 0 ration while the carriage is being shifted from one ordinal position to another, and to accomplish these ends the followin mechanism is employed.

As t shown in Figs. 1, 4 and 5, there is fastened to the slideways 75 an angle plate 219, the horizontal flange 220 of which extends forwardly and is provided at its for'- ward edge-with notches 221 spaced apart a distance equal to that between two adjoining banks of keys 27. Fastened centrally on the shaft 214 is a vertical 'arm 222, which when the machine is in normal condition, is in alignment but out of engagement with, one of the notches 221, dependent upon the columnar position of the control carriage, so that the control carriage is free to be shifted to another ordinal position by the hand wheel 115. The goose neck arm 213 (Fig. 4) fast on the right hand end of the shaft 214, carries a pin 223, proj ecting into a slot 224 formed in one arm of a bell-crank 225 pivoted on one of the screw studs 34. The rear free end of the other arm of this lever is normally in front of a square block 226 secured to the inner side of the cam 1 plate 52. During operation of the machine,

when the arm 213 is rocked forwardly by the spring 216', as above described, the shaft 214 and arm 222 are rocked clockwise to the positions shown in Fig. 11, whereby the arm 222 is moved rearwardly into-engagement with one-of the notches 221, hence locking the control carriage against columnar shifting movement during operation of the operating crank 56. During this forward movement of the arm 213, the bell-crank lever 225, because of the pin-and-slot connections 223 and 224, is rocked to the position shown in Fig. 11 so that its rear end is moved out of the path of movement of the block 226 on the cam plate 52 to permit operation of crank 56, there being sufficient clearance normally between the rear end of the lever 225 and block 226 to permit the end of the lever to be moved away from in front of the block during the first increment of movement of operation of the cam plate 52 by the crank 56. During shifting movement of the control carriage from one ordinal position to another, the notches 221 areout of alignment with the arm 222 so that, should an attempt be made at such time to operate the o crating crank 56, the forward edge of the ange 220 between the notches would block movement of the arm 2.22 and hence prevent movement from normal position of the arm 213 and the bell-crank 225 by the spring 216 and, as the lever 225 would thus be held in'its normal position, its rear end, being in front of the lug or block 226,

would block movement of the cam plate 52 and hence of the operatingcrank 56.

It is also desirable to prevent operation of the machine while the finger piece 126 and associated levers 1-23 and 128 are being moved from one postion to another, during which time the carriage plate 76 is shifted relative to the slideway 75 to condition the machine for substraction (division) or addition (multiplication), as the case may be. To this end the lower end of the lever 123 is provided with an extension 230 (Figs. 1 and 5) projecting into a notch 231 in a slide-plate 232 mounted for sliding movement on the flange 220 by means of screw studs 233 threaded into the flange 220 and projecting through slots 234 in the plate 232. This plate 232 has six pairs of notches 235 in its front edge, so spaced that the right-hand (as viewed in Fig. 1) notches of the pairs register with the notches 221 in the flange 220 when the carriage control plate 76 is set for addition, and the lefthand notches of the pairs register with the notches 221 when the control carriage plate 76 is set for substraction, the plate 232 being shifted from one position to the other by the lever 123, when the machine is conditioned accordingly for addition or subtraction by the finger-piece 126. During the time the carriage plate 76 is being shifted from adding to subtracting position, or vice versa, the projections of the plate 232 between the notches of the pairs are in alignment with the notches 221 in the flange 220 and their outer ends form abutments which prevent entrance of the locking arm 222 into the notches 221 until the carriage plate 7 6 has traveled its full movement to either substractive or additive condition.

Shiftable pointers for accumulator wheels and counter wheels track 238 with a slidable pointer 239 mounted thereon, as shown in Fig. 1. A similar pointer 240 is mounted to slide on a track 241 positioned on the cover. 150 and above the sight-openings therein for the purpose of pointing off the proper number of decimal places in the quotient as will be described presently more fully in connection with the description of the operation of the machine in performing a problem in division. 

